Modelling of a thin soft layer on a self-lubricating ceramic composite

Valefi, M.; Rooij, M.B. de; Mokhtari, Milad; Schipper, Dirk J.

doi:10.1016/j.wear.2013.02.017

Cited by 24 publications

(9 citation statements)

References 35 publications

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“…In the aforementioned friction modeling work [6,7,[9][10][11][12][13][14][15], a coated surface was indented by a hard indenter. This may result in severe abrasive friction and wear due to plowing [19]. A good tribological design should avoid such indentation and hence, in the present study flattening, instead of indentation, of coated spherical contact that causes mild adhesive friction and wear is preferred.…”

Section: Introductionmentioning

confidence: 97%

Model for the static friction coefficient of spherical contact with a soft metal coating

2020

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An elastic-plastic spherical contact with soft metallic coating under combined normal and tangential loading is studied by finite element analysis. Full-stick contact condition is assumed and sliding inception is related to vanishing tangential stiffness of the contact junction. Previously observed, both experimentally and theoretically, effects of increasing coating thickness on static friction coefficient that were published in the literature are thoroughly explained here, to the authors' best knowledge, for the first time. These effects include initial sharp drop of friction as soon as a thinnest coating film is applied, followed by a transitional behavior from decrease to increase of friction when the coating thickness is continuously increased. An intensive parametric study is performed and the effects of substrate and coating material properties on the static friction coefficient are revealed and thoroughly explained. An empirical expression for the static friction coefficient is derived along with the values for optimum coating thickness that provides the minimum friction coefficient.

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Section: Introductionmentioning

confidence: 97%

Model for the static friction coefficient of spherical contact with a soft metal coating

2020

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“…The concept of formation and removal of a thin layer with different properties than the bulk of the material, the competition between these two phenomena and the balance between them has been studied for other materials such as ceramics [34] or steel components in the boundary lubrication regime and at presence of lubricant additives [35]. The sliding resistance of an elastomer in contact with a rigid rough surface is dependent on the nature of the interface which is prone to changing because of the frictional energy dissipation during use.…”

Section: Discussionmentioning

confidence: 99%

Existence of a Tribo-Modified Surface Layer on SBR Elastomers: Balance Between Formation and Wear of the Modified Layer

et al. 2015

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In most of the tribological contacts, the composition and tribological properties of the original interface will change during use. The tribo-films, with modified properties compared to the bulk, are dynamic structures that play a significant role in friction. The existence of a tribo-modified surface layer and its importance on the overall friction of elastomers has been shown both theoretically and experimentally before. The characteristics of the modified surface layer deserve specific attention since the tribological properties of elastomers in contact with a rough counter-surface are determined by these modified surfaces together with the properties of bulk of the material. Both the formation of the modified layer and the break down (wear) of it are of importance in determining the existence and thickness of the tribo-modified layer. In this study, the importance of the wear is emphasized by comparing two styrene butadiene rubber-based elastomers in contact with a granite sphere. A current status of perception of the removal and the stability of the modified surface layers on rubbers is introduced as well as experimental work related to this matter and discussion within literature. Pin-on-disk friction tests are performed on two SBR-based samples in contact with a granite sphere under controlled environmental conditions to form the modified surface layer. Although the hysteresis part of the friction force which has a minor contribution in the overall friction is not markedly different, the total measured friction coefficient differs significantly. Mechanical changes both inside and outside the wear track are determined by atomic force microscope nano-indentations at different timescales to examine the modified surface layer on the test samples. The specific wear rates of the two tribo-systems are compared, and the existence of the modified surface layer, the different measured friction coefficient and the running-in distances toward steady-state friction are explained considering different wear rates. A conceptual model is presented, correlating the energy input into the tribo-system and the existence of a modified surface layer.

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“…The stability of the formed solid lubricant layers at the interface during sliding relies on the hardness of the matrix or any secondary additives [ 25 , 26 ]. In general, solid lubricant materials are soft in nature.…”

Section: Introductionmentioning

confidence: 99%

Friction and Wear Behavior of Alumina Composites with In-Situ Formation of Aluminum Borate and Boron Nitride

Kasar

Menezes

2020

Materials

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Wear and friction properties of Al2O3 composite reinforced with in-situ formed aluminum borate (9Al2O3·2B2O3) and hexa-boron nitride (h-BN) have been investigated. The initial constituents for the composites were Al2O3, AlN, and H3BO3. The H3BO3 was used as a source of B2O3, where B2O3 reacted with AlN and Al2O3 to form in-situ h-BN and 9Al2O3·2B2O3. Based on the thermodynamic calculation and phase transformation, four different compositions were selected. First, the powders were mixed by ball milling followed by compaction at 10 MPa. The compacted pellets were sintered at 1400 °C in vacuum. The composites were characterized using X-ray diffraction followed by hardness measurement and reciprocating sliding test against alumina and steel balls. The X-ray diffraction results revealed the formation of in situ phases of 9Al2O3·2B2O3 and h-BN that improved the tribological properties. By comparing the tribological performance of different composites, it was found that the hard 9Al2O3·2B2O3 phase maintains the wear resistance of composites, whereas the coefficient of friction is highly dependent on the counter ball. Against alumina ball, the lowest coefficient of friction was observed for the composites with maximum h-BN concentration and minimum aluminum borate concentration, whereas the opposite trend was observed against the steel ball.

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Modelling of a thin soft layer on a self-lubricating ceramic composite

Cited by 24 publications

References 35 publications

Model for the static friction coefficient of spherical contact with a soft metal coating

Model for the static friction coefficient of spherical contact with a soft metal coating

Existence of a Tribo-Modified Surface Layer on SBR Elastomers: Balance Between Formation and Wear of the Modified Layer

Friction and Wear Behavior of Alumina Composites with In-Situ Formation of Aluminum Borate and Boron Nitride

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